If you go to the nightly link (Actions · darktable-org/darktable · GitHub) . You will see this:
Green checkmark means it was successful at doing the build. Red that it had some issue. Dont use the red.
If you click in the top green one it will open this page:
At the bottom it has a zip file. The zip file has the windows install .exe file. You need to login to GitHub to be able to click the file and download it. After that install it just like Bill’s build.